Matrix inversion techniques utilized in attempts to solve this problem before have yielded poor results because of the instability of the mathematical model and the indeterminate nature of the required matrix inversion. Simple triangulation methods fail because of discontinuities and insufficient baseline lengths to provide adequate accuracy. A Gauss-Newton estimation procedure has been the classic approach to the problem. (See Ortega and Rheinboldt, infra, at p. 267.) This incorporates the use of quasi-linear estimation techniques. The short baseline lengths of these systems account for excessive sensitivity of trajectory parameters on very small range errors, manifested in a highly ill-conditioned covariance matrix, making the estimate inaccessible.